Sulfur containing organosilicon compounds are useful as reactive coupling agents between rubber and silica fillers providing for improved physical properties. They are also useful as adhesion primers for glass, metals and other substrates.
U.S. Pat. Nos. 3,842,111, 3,873,489 and 3,978,103 disclose the preparation of various sulfur containing organosilicon compounds. These organosilicon compounds are prepared by reacting
(a) 2 moles of a compound of the formula EQU Z--Alk--hal PA1 (b) 1 mole of a compound of the formula EQU Me.sub.2 S.sub.n PA1 (i) 100 parts by weight of at least one sulfur vulcanizable elastomer selected from conjugated diene homopolymers and copolymers and from copolymers of at least one conjugated diene and aromatic vinyl compound; PA1 (ii) 10 to 250 phr of particulate precipitated silica; PA1 (iii) 0.05 to 15 phr of a compound of the formula ##STR4## PA1 in which Z is selected from the group consisting of ##STR8##
where hal is a chlorine, bromine or iodine; Z is ##STR2##
where R.sup.1 is an alkyl of 1 to 4 carbon atoms or phenyl and R.sup.2 is alkoxy of 1 to 8 carbon atoms; or cycloalkoxy of 5 to 8 carbon atoms; or alkylmercapto with 1 to 8 carbon atoms; Alk is a divalent aliphatic hydrocarbon or unsaturated hydrocarbon or a cyclic hydrocarbon containing 1 to 18 carbon atoms; with
where Me is ammonium or a metal atom and n is a whole number from 2 to 6.
U.S. Pat. No. 4,820,751 and Japanese Patent Application 124400-1984 disclose the use of an asymmetrical siloxy compound in a silica-filled rubber. Representative asymmetrical siloxy compounds contain a benzothizole moiety or thiocarbamyl moiety.